As Aerovistae writes, the first one appears to be far and away the most common wording.
In the past, however, the second appears to have been more common and still sees some use today. This is not surprising, since the syntactic status of rien is not simple (see CNRTL entry), overlapping with noun phrase types, and parsing it as something closer to a direct object would of course place it after pu and any other modal. It seems that for several decades it has been parsed much more as a negative particle, like pas.
When you see lines cross on an Ngram like that... you're watching diachronic (historical) linguistics in action :)